Electromagnetic Interference (EMI) is a disturbance that interrupts, obstructs, degrades, or limits the effective performance of electronics and electrical equipment. It can occur unintentionally as a result of spurious emissions and responses. Electromagnetic compatibility (EMC) tries to ensure that equipment items or systems will not interfere with or prevent the correct operation of other equipment items or systems through emission or absorption of EMI. The damaging effects of EMI pose unacceptable risks in many areas of technology and it is necessary to control EMI and reduce the risks to acceptable levels. Printed circuit boards (PCBs) are often mounted to chassis and may emit and receive EMI.